Have you heard of
square foot gardening? Building a raised bed with the intent of close plantings? I wouldn't use their potting mix, I'd use good garden soil and compost, and plant it so anything larger can grow off of the side and expand outward.
Wikipedia entry on square foot gardening.
The fellow who started this is
Mel Bartholomew, and there was a program on PBS back in the 1980s.
Visit the Dirt Doctor
organic guides for information about bed preparation and use the
Library of Organic Information to find information on fertilizing, pest control, etc. and you should be fine.